1. Field of the Invention
The present invention relates to protective apparatuses, and particularly to a protective apparatus that protects device connected to an AC circuit from being damaged if there is a misconnections between a live line and an earth line.
2. General Background
Most electric equipment, such as household appliances and factory machines, are generally powered by a three-phase AC power system. The AC power system generally includes a live (hot) line, a neutral line, and an earth line. The live line and the neutral line are for providing power to the electric equipment. The earth line is grounded.
It is known that line mismatches in a circuit may happen, and equipment connected to the circuit may be damaged. Conventionally, safe fuses are connected to the live line and the neutral line. If too much power is drawn by the circuit, the safe fuse is melted to break the circuit so that the equipment connected to the circuit is protected. It is simple but costly to use safe fuses to protect the equipment, and the safe fuses may have a slow response time and lack the necessary sensitivity required for proper protection of the circuit and the attached equipment. Additionally, it is costly and troublesome to replace melted fuses with new ones.
What is desired, therefore, is a protective apparatus which sensitively and conveniently protects device connected to an AC circuit.